package com.common.system;


import java.awt.BasicStroke;
import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Random;

import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

public class CaptchaServlet extends HttpServlet {  

  private static final long serialVersionUID = 1L;  

  public CaptchaServlet() {  
      super();  
  }  

  public void destroy() {  
      super.destroy();   
  }  

  public void init() throws ServletException {  
      super.init();  
  }  
  /*该方法主要作用是获得随机生成的颜色*/   
  public Color getRandColor(int s,int e){  
      Random random=new Random ();  
      if(s>255) s=255;  
      if(e>255) e=255;  
      int r,g,b;  
      r=s+random.nextInt(e-s);    //随机生成RGB颜色中的r值  
      g=s+random.nextInt(e-s);    //随机生成RGB颜色中的g值  
      b=s+random.nextInt(e-s);    //随机生成RGB颜色中的b值  
      return new Color(r,g,b);  
  }  

  @Override  
  public void service(HttpServletRequest request, HttpServletResponse response)  
          throws ServletException, IOException {  
	// 禁止缓存

      response.setHeader("Pragma", "No-cache");
      response.setHeader("Cache-Control", "No-cache");
      response.setDateHeader("Expires", 0);
//指定生成的响应是图片
      response.setContentType("image/jpeg");
      int width = 100;
      int height = 30;
      BufferedImage image = new BufferedImage(width, height,
              BufferedImage.TYPE_INT_RGB); // 创建BufferedImage类的对象
      Graphics g = image.getGraphics(); // 创建Graphics类的对象
      Graphics2D g2d = (Graphics2D) g; // 通过Graphics类的对象创建一个Graphics2D类的对象
      Random random = new Random(); // 实例化一个Random对象
      Font mFont = new Font("华文宋体", Font.BOLD, 30); // 通过Font构造字体
      g.setColor(getRandColor(200, 250)); // 改变图形的当前颜色为随机生成的颜色
      g.fillRect(0, 0, width, height); // 绘制一个填色矩形
//画一条折线
      BasicStroke bs = new BasicStroke(2f, BasicStroke.CAP_BUTT,
              BasicStroke.JOIN_BEVEL); // 创建一个供画笔选择线条粗细的对象
      g2d.setStroke(bs); // 改变线条的粗细
      g.setColor(Color.DARK_GRAY); // 设置当前颜色为预定义颜色中的深灰色
      int[] xPoints = new int[3];
      int[] yPoints = new int[3];
      for (int j = 0; j < 3; j++) {
          xPoints[j] = random.nextInt(width - 1);
          yPoints[j] = random.nextInt(height - 1);
      }
      g.drawPolyline(xPoints, yPoints, 3);

//生成并输出随机的验证文字

      g.setFont(mFont);

      String sRand = "";

      int itmp = 0;

      for (int i = 0; i < 4; i++) {
          if (random.nextInt(2) == 1) {
              itmp = random.nextInt(26) + 65; // 生成A~Z的字母

          } else {
              itmp = random.nextInt(10) + 48; // 生成0~9的数字
          }
          char ctmp = (char) itmp;
//          sRand += String.valueOf(ctmp);
//          Color color = new Color(20 + random.nextInt(110),
//                  20 + random.nextInt(110), 20 + random.nextInt(110));
//          g.setColor(color);
///**** 随机缩放文字并将文字旋转指定角度 **/
////将文字旋转指定角度
//          Graphics2D g2d_word = (Graphics2D) g;
//          AffineTransform trans = new AffineTransform();
//          trans.rotate(random.nextInt(45) * 3.14 / 180, 15 * i + 10, 7);
////缩放文字
//          float scaleSize = random.nextFloat() + 0.8f;
//          if (scaleSize > 1.1f)
//              scaleSize = 1f;
//          trans.scale(scaleSize, scaleSize);
//          g2d_word.setTransform(trans);
///************************/
          sRand+=String.valueOf(ctmp);
          g.drawString(String.valueOf(ctmp), 20 * i , 20);
      }
//将生成的验证码保存到Session中
      HttpSession session = request.getSession(true);
      session.setAttribute("randCheckCode", sRand);
      g.dispose();
      ImageIO.write(image, "JPEG", response.getOutputStream());
  }  
}  
